Trends in Intensity Change and Translation Speed of Landfalling North American Tropical Cyclones

Keywords: climatology, tropical cyclones, landfalls, hurricanes, intensity change, translation speed, North Atlantic, eastern North Pacific
Abstract Type: Paper Abstract

Abstract

In this study, we analyze 50-years (1971–2020) of tropical cyclone (TC) data from the North Atlantic (NATL) and eastern North Pacific (ENP) basins to assess trends in the characteristics of landfalling TCs. Specifically, we focus on landfall intensity change (LIC, the difference between a TC's intensity at landfall versus t hours before landfall), mean translation speed (MTS, the average translation speed of a TC during the final t hours prior to landfall), and magnitude of translation speed change (ΔTS, the difference between the translation speed at landfall versus t hours before landfall). For each landfalling TC, we calculate LIC, MTS, and ΔTS for the final 12, 24, and 36-hours before landfall. To assess trends, we segment the coast into seven segments, two in the ENP and five in the NATL. we employ the Thiel-Sen Slope estimator, a non-parametric test, to understand how each variable has been changing with time for each segment. For LIC, we then define extreme intensification (EI) and weakening (EW) as the 90th and 10th percentile of all LICs for each time period. We analyze trends in EI and EW using a Poisson Regression. Results from this study will help better understand the changing behavior of landfalling TCs with time and provide additional context of recent extreme TCs, including NATL Hurricane Laura in 2020 and ENP Hurricane Willa in 2018.